A series of experiments are proposed to investigate the manner in which people's metacognitions, that is, their expectations and predictions about future performance, impact upon their problem- solving performance. The major goal of research is to contribute to our understanding of human problem-solving processes and the interrelation of these processes with the metacognitive system. Four specific aspects of the relation between metacognitions and problem solving will be investigated: (1) the use of online metacognitive monitoring to differentiate insightful from incremental cognitive operations used in problem solving, (2) the validity of metacognitions as an index of different cognitive operations that may be used in the same task, (3) the effect of general expectations on specific metacognitions that strategically control problem solving behavior, and (4) the focus of expectation-related performance deficits. The results of these experiments have implications not only for our basic understanding of higher cognitive function and dysfunction, but also for enhancing human cognitive performance.